Maycock, AC orcid.org/0000-0002-6614-1127, Masukwedza, GIT, Hitchcock, P et al. (1 more author) (2020) A Regime Perspective on the North Atlantic Eddy-Driven Jet Response to Sudden Stratospheric Warmings. Journal of Climate, 33 (9). pp. 3901-3917. ISSN 0894-8755
Abstract
Changes to the preferred states, or regime behavior, of the North Atlantic eddy-driven jet (EDJ) following a major sudden stratospheric warming (SSW) is examined using a large ensemble experiment from the Canadian Middle Atmosphere Model in which the stratosphere is nudged toward an SSW. In the 3 months following the SSW (January–March), the North Atlantic EDJ shifts equatorward by ~3°, on average; this arises from an increased occurrence of the EDJ’s south regime and reductions in its north and central regimes. Qualitatively similar behavior is shown in a reanalysis dataset. We show that under SSW conditions the south regime becomes more persistent and that this can explain the overall increase in the EDJ latitude decorrelation time scale. A cluster analysis reveals that, following the SSW, the south EDJ regime is characterized by weaker low-level baroclinicity and eddy heat fluxes in the North Atlantic Ocean. We hypothesize, therefore, that the increased persistence of the south regime is related to the weaker baroclinicity leading to slower growth rates of the unstable modes and hence a slower buildup of eddy heat flux, which has been shown to precede EDJ transitions. In the North Atlantic sector, the surface response to the SSW projects onto a negative North Atlantic Oscillation (NAO) pattern, with almost no change in the east Atlantic (EA) pattern. This behavior appears to be distinct from the modeled intrinsic variability in the EDJ, where the jet latitude index captures variations in both the NAO and EA patterns. The results offer new insight into the mechanisms for stratosphere–troposphere coupling following SSWs.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2020 American Meteorological Society. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | Dynamics, Jets, Stratosphere-troposphere coupling, Climate variability, Climate models, North Atlantic Oscillation |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst for Climate & Atmos Science (ICAS) (Leeds) |
Funding Information: | Funder Grant number NERC (Natural Environment Research Council) NE/M018199/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 14 Feb 2020 11:29 |
Last Modified: | 06 Oct 2020 00:38 |
Status: | Published |
Publisher: | American Meteorological Society |
Identification Number: | 10.1175/JCLI-D-19-0702.1 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:157059 |